hist-brewing: Malt, starch, sugar and adjuncts / alcohol tolerant yeast

George de Piro gdepiro at mindspring.com
Fri Jun 23 20:19:14 PDT 2000


Hi all,

There have been a few misconceptions written in the thread about the use of
starchy adjuncts like potatoes.

Malt is starchy.  The vast majority of starch conversion does not take place
during malting.  Malt must be mashed with hot water to saccharify the
starches.  When using starchy adjuncts, like rice, corn, potatoes, etc.,
they are first gelatinized by heating and then added to the mash to
saccharify the starch.

Certain malts, like crystal malt, are made in a manner that converts much of
the starch to sugar and then caramelizes it (which is why it looks glassy).
Most malts are quite starchy, though.

Using starchy adjuncts like potatoes, rice and corn add little (if any)
flavor to the beer.  They are used to maintain a beer's alcoholic strength
while leaving the color, flavor and body very light.  Sugary adjuncts are
used to similar effect without having to mash them.

Regarding yeast and alcohol tolerance:  most brewing yeast is very alcohol
tolerant when it is treated with the respect it deserves.  That means
pitching high quantities of healthy yeast (something which many homebrewers
do not do).  How does one obtain a big crop of healthy yeast?

1.  Go to your local brewery and ask them for yeast.  I give yeast to
homebrewers all the time, and most other brewpub brewers will do the same.
This is by far the easiest way to get yeast.

2.  Grow the yeast yourself.  It's not hard.  I wrote an article for Brewing
Techniques (RIP), Jan. 1998, about yeast propagation.  If you don't have it,
here are some basic rules:

Step yeast up in no more than 10X increments.  That means that if you are
starting with a 50 mL Wyeast smack pack, it should be added to no more than
500 mL (~1 pint) of wort.  Aerate very well (pure oxygen works best, a stir
plate is your next best bet, and shaking by hand - a lot - will work if you
must).  It will take about a day for the yeast to ferment the starter.  The
next day the 500 mL starter can be stepped up to 5 L, but most homebrewers
step up to 2 L (half gallon).  Aerate well and the next day you are ready to
brew a batch up to 20 L (~5 gallons).

If you are making a very strong beer (or mead), this will not yield enough
yeast to guarantee that your ferment will not end prematurely.  As both a
home- and commercial brewer I make a normal gravity beer with the freshly
propagated yeast, harvest the yeast out of the fermentor and add the rather
large quantity to the high-gravity wort.  In this way I have a lot of yeast
for the big beer.

Oxygen is vital to yeast during propagation.  Yeast use it to make sterol,
an important part of the cell membrane.  Yeast can only contain a maximum of
1% sterol (by weight).  They need at least 0.1% sterol to be able to live.
Each time the yeast divides they give half the sterol to the daughter cell.
That means that a cell can only divide 3 times before they are limited from
further reproduction by a lack of sterol.

If you pitch too little yeast, three divisions will not yield enough yeast
to quickly (and palatably) ferment your wort.  You will end up with an
abbreviated ferment and very sweet beer (or mead).  If you think that adding
oxygen to the young beer is an option, think again:  the oxygen can cause
oxidation, producing papery and buttery flavors.  Another problem is that
growing yeast and brewing beer are not the same thing.  The liquid made in a
yeast propagator that has been aerated a lot does not taste as pleasant as
beer (high yeast growth rates always equal high levels of harsh fusel
alcohols).

By following proper yeast propagation procedures you will find that your
beers and meads will taste better faster, with fewer harsh fusel alcohols
and esters.  In fact, it is a myth that meads and barley wines need months
of aging to be drinkable.  While they often do benefit from aging, they
should at least be very palatable when young.  Aging should only be needed
to build depth and complexity.

Hope that helped, have fun!

George de Piro

C.H. Evans Brewing Company
at the Albany Pump Station
(518)447-9000
http://evansale.com

Malted Barley Appreciation Society
Homebrew Club
http://hbd.org/mbas


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